Patent GB-371542-A (GB)
Title: Improvements in hydraulic driving means for vehicles having multi-wheel drive
IPC: B60K17/10
Filed: 1931-03-10
Abstract: 371,542. Hydraulic transmission for motor vehicles. MONTELIUS, C. O. J., 20, Norr Mõlarstrand, Stockholm. March 10, 1931, No. 7421. [Class 79 (ii).] Driving gearing for motor vehicles having at least three separately driven wheels comprises at least one hydraulic motor for each driving wheel, a prime mover driving a pump which supplies the hydraulic motors, and a valve device for varying the number of. active motors, the said active motors being always in parallel. In the construction shown a petrol engine 1 drives a pump 2, which may be of the double-screw type described in Specification 231,865, [Class 110 (i), Centrifugal and screw fans &c.], connected by supply conduits 3, 4 and return conduits 19, 20 to valve boxes 13, 14 of hydraulic motors 5 .. 8 driving the four road wheels independently. The motors may also be of the double-screw type, as shown, and each motor drives its corresponding road wheel through universal joints 22. the rear motors 7, 8 are preferably of 50 per cent greater tractive power than the front motors, and the valve boxes 13, 14 and a valve 58 in the pump are so controlled that the following combinations are available: (1) The front motors only are driven, and the vehicle is driven at its highest speed. (2) The rear motors only are driven, the speed being about two-thirds of that obtained when the front wheels only are driven. (3) The front and rear motors are driven in parallel, the speed being about 40 per cent of the maximum, and the tractive effort being 2.5 times that obtained with frontwheel drive alone. (4) The front and rear motors are driven in the reverse direction in parallel. (5) A " no-drive " position can be obtained by operating the valve 58 in the pump casing so as to connect the suction and delivery passages together. (6) Braking of the vehicle is effected by operating the valve 58 so as to throttle or close the return conduits from the motors to the pump. Instead of the front and rear motors being of different capacities they may be of equal size but may drive the road wheels through gear trains of different ratios. The positions of the valve and controlling levers for the front-drive arrangement is shown in Figs. 3 and 7. The motor valves 46, 47 are controlled by floating levers 25, 26 operated by a hand-lever 43 through a crank 23 and rods 24, the pivots 29, 30 of the floating levers being connected by links 44, 45 to levers 27, 28 pivoted to the frame at 31, 32 and controlled by springs 66, 67 so as to force rods 33, 34 provided with rollers 36, 37 towards a disc rotatable by a pedal 39. The disc 35 is provided with two recesses 68, 69 for the reception of the rollers 36, 37. In the position shown in Figs. 3 and 7 the hand-lever 43 is inclined to the left and moves the rods 24 to the right, thus tending to move the valves 46, 47 to the left. The pedal 39, however, is in such a position that the roller 37 lies in the recess 69 so that the rod 34 moves to the left and counteracts the movement of the right-hand' rod 24 to the right, the result being that the valve 47 is left in the central or neutral position and the valve 46 is moved to the left. Under these conditions (1) the conduit 4 is cut off by the valve 47 from both valve passages 59, 65 leading to the rear motors 7, 8, and (2) liquid passes from the pump through conduit 3 to passages 50, 57 in valve 46 and thence to the motors 5, 6 returning to the pump through passage 52, the interior of the valve, and conduit 19. To drive the rear motors only the pedal 39 is partly depressed, the recess 69 moves away from roller 37 so that the rod 34 moves to the right and the valve 47 to the left into the forward drive position ; the recess 68 comes under the roller 36 and allows the rod 33 to move to the right, thus moving the valve 46 to the central or neutral position. To drive both front and rear motors the pedal 39 is further depressed so that both rollers 36, 37 are out of the recesses 68, 69 ; the valves 46, 47 are thus both placed in the left-hand or forward drive position. To drive front and rear motors in the reverse direction the handlever 43 is inclined to the right and the pedal 39 is left in the forward-drive position just described, the valves 46, 47 are moved to the extreme right, and both sets of motors 5 .. 8 are driven in the reverse direction. The pedal 39 is normally held in the position shown in Fig. 7 by means of springs 72, 71, and a floating lever 74 moving between stops 78, 79, 80 and pivoted to an arm 70 on a shaft 75 carrying a lever 76 which operates the valve 58 in the pump casing. When the hand-lever 43 is placed in a vertical position a cam 85 operated by the hand-lever acts on the lower end of lever 76, as shown in Fig. 7a, and moves the valve 58 slightly to the right, thus establishing a connection by a byepass 83 between the suction and delivery sides of the pump, and thereby stopping the transmission of power. The same effect may be obtained by depressing the pedal 39 to the position shown in Fig. 10, the spring 72, in conjunction with stop 79, acting on the lever 74 in such a way that the shaft 75 is rotated and the valve 58 operated. To brake the vehicle the pedal 39 is still further depressed, the lever 74 is brought against stops 79, 80, and the valve 58 is moved to the extreme right thus closing the return conduit 19 from the motors while the byepass 83 freely connects the suction and delivery of the pump. Thus, as long as the road wheels are rotating, the motors act as pumps against the closed valve 58 which they can open to a certain extent against the force of the spring 72.